Extraction of protein from seed

ABSTRACT

A process of making foodstuffs (e.g., simulated meats) by the steps of mixing a coprecipitate of protein and lipid in the presence of water with an edible water-soluble salt, then heatsetting this mixture and, during or subsequent to setting, contacting the mixture with a lipid solvent.

United States Patent 11 1 Newsom et al.

' 1 Feb. 26, 1974 EXTRACTION OF PROTEIN FROM SEED Inventors: BrianGeorge Newsom, Pertenhall;

Michael Peter Tombs, Pavenham,

both of England Assignee: Lever Brothers Company, New

York, NY.

Filed: Sept. 16, 1971 Appl. No.: 181,263

Foreign Application Priority Data Oct. 9, 1970 Great Britain 48,072/70US. Cl 426/364, 260/123.5, 426/417,

426/431, 426/424 Int. Cl. .f. A23j 3/00, A231 1/20 Field of Search99/17, 14, 98, 20 E;

Primary Examiner-A. Louis Monacell Assistant Examiner Wi1liam AndrewSimons Attorney, Agent, or FirmLouis F. Kline, Jr. et a1.

[57] ABSTRACT A process of making foodstuffs (e.g., simulated meats) bythe steps of mixing a copreclpitate of protein and lipid in the presenceof water with an edible watersoluble salt, then heat-setting thismixture and, during or subsequent to setting, contacting the mixturewith a lipid solvent.

6 Claims, No Drawings EXTRACTION OF PROTEIN FROM SEED This inventionrelates to the extraction of protein from protein-bearing seed.

Protein-bearing seed, for example soybeans and groundnuts, containslipid and water-insoluble carbohydrate in addition to protein, and inextracting protein from the seed it is customary first to extract thelipid by treatment at low temperature with a lipid-solvent, such ashexane, and then to extract protein from the meal thus obtained. Theresulting concentrate can be used in the manufacture of food products.

The present invention provides a process for the extraction of proteinfrom protein-bearing seed which avoids the low-temperature extraction ofseed with a lipid solvent, and yields a fluid lipid-containing proteinmaterial which can be used in the manufacture of food products.

In the first stage of the process of the invention, the seed is finelysubdivided, and from the subdivided material an aqueous emulsion ofprotein and lipid is formed which contains in suspension thewaterinsoluble carbohydrate of the seed. In carrying out the firststage, the seeds are treated to split or remove the bulls and leave thecotyledons exposed, and these are finely subdivided in the presence ofwater, conveniently by passing them with water through a homoge' niserequipped with cutters. Alternatively, whole (unhulled) seeds can befinely ground in the presence of water in a mill. Disintegration of thecotyledons releases powerful emulsifying agents naturally occurring inthem, and under the action of these agents the protein and lipid of theseeds become emulsified.

It is desirable to include in the water employed a small proportion,suitably from 0.01 to 5 percent by weight, of a dissolved agent (such asa water-soluble, sulphite, bisulphite or dithionite) that prevents thelinking of protein SH groups to form intermolecular-S-S linkages. Bythis means one can prevent the aggregation of protein molecules thattends to occur in aqueous protein systems and often results in gelation.

The aqueous emulsion of protein and lipid formed by the above procedureis then treated to remove from it the water'insoluble carbohydrate thatit contains in sus pension. This is best done by centrifugation.

The supernatant protein-lipid emulsion is then acidifled to reduce itspH to a value at which the protein becomes precipitated. The pH chosenwill be in the vicinity of the isoelectric pH of the protein componentof the emulsion; with soy protein, for example, the pH of the emulsionis reduced to a value in the range 4.2 5.5. The use of hydrochloric orsulphuric acid as precipitant is preferred. The protein component of theemulsion is not precipitated alone, but brings down with it a fairlyhigh proportion of the lipid component;

7 that is to say, a coprecipitate of protein and lipid is formed. Thisprecipitated material is separated from the supernatant liquid, suitablyby centrifugation, and is obtained in the form of a cake, usually ofsolids content in the range 30 60 percent by weight.

The separated coprecipitate of protein and lipid is then mixed with anedible salt; this, when used in at least the minimum proportion definedin the next paragraph, has the effect of converting the solid proteinpresent in the coprecipitate into a fluid aqueous preparation of proteinconcentration at least percent by weight and usually in the range 15 50percent. This fluid aqueous preparation is rather viscous and containsdistributed in it the lipid present in the coprecipitate, and it can beutilised in the manufacture of food products.

The edible salt employed is preferably sodium chlor ide, but otheredible salts can be used if desired, for example sodium phosphate,potassium chloride and calcium chloride. The salt is used in an amountsuch that the fluid aqueous preparation that. is formed from it and fromthe separated coprecipitate and associated water contains dissolvededible salt in a concentration equivalent to an ionic strength of atleast 0.2. The ionic strength is calculated from the ion concentrationsand the water content of the fluid aqueous preparation, in accordancewith the well-known equation Ionic strength /EQZ where C, molarconcentration of each ion Z, valence of each ion Thus, for a fluidaqueous preparation containing 27% percent protein, 15 percent lipid, 5percent other organic material (such as water-soluble carbohydrate), 2percent sodium chloride, /2 percent calcium chloride, and 50 percentwater, the ionic strength based on the water content is /2 (0.68 X 10.68 X 1 +0.09 X 2 0.18 X1 0.95

To utilise the fluid lipid-containing aqueous protein preparation in themanufacture of food products, it is subjected to conditions under whichit becomes solidified or set owing to setting of the protein content.Setting is preferably brought about by heat. The product obtained bysolidifying the preparation will usually have a pronounced flavor of theseed from which it is derived (for example, flavor of soy bean), andsuch a product is accordingly best made use of in dishes (such ascurries) which have a flavor of their own pronounced enough to mask theseed flavor. However, we have found that if the preparation is during orsubsequent to solidification exposed to a lipid-solvent so that part ofthe lipid content is dissolved and the protein/- lipid ratiocorrespondingly increased, then the seed flavor is markedly reduced; theutility of the product is then correspondingly widened. The preferredprocedure consists in extruding the fluid aqueous preparation into asetting medium maintained at a temperature of at least C. If alipid-solvent is used as setting medium, the setting of the protein anddissolution of the lipid are substantially simultaneous. The lipidsolvent employed may, for example, be isopropanol or isopropanol-watermixtures. If the setting medium used is not a lipid solvent, then theextruded set material can be treated with a lipid-solvent to .reduce itslipid content. By extruding through spinnerets of small diameter, fiberscan be obtained, and these can be used as an ingredient of manufacturedfood products, especially as part-replacement for meat.

The following Examples further illustrate the invention as applied tosoybeans.

Example 1 This Example, and Example 2, illustrate the treatment ofsoybeans to obtain a fluid aqueous protein preparation containing lipid.

Dehulled soy beans (250g) were passed with aqueous 0.1 percent sodiumsulphite (2.5 litres) through a homogeniser fitted with blades, and theaqueous emulsion of protein and lipid thus formed was centrifuged at 500X g for 30 minutes to remove suspended water- 5 insoluble carbohydrate.The pH of the supernatant emulsion was then reduced by addition of anacid reagent to a value in the range 5.5 4.2, and the coprecipitate ofprotein and lipid thus obtained was centrifuged at 500 X g for minutes.The moist separated precipil0 tate (cake) of protein and lipid wasanalysed, with the results shown below:

traces of solid carbohydrate and was extruded through spinnerets ofdiameter 0.2 mm into a setting bath maintained at 75 80C. In fourseparate procedures, the setting baths and the composition:

i. isopropanol ii. 75% isopropanol, 25% water iii. 50% isopropanol, 50%water iv. 25% isopropanol, 75% water The c omposition of the fibresproduced is shown be low, and'compared with that of the aqueouspreparation from which they were obtained by extrusion.

COMPOSITION OF FlBRES Total Protein/ Water solids Protein Lipid Ashlipid Fibres iv 56.0 44.0 31.2 9.6 0.5 3.24

' Composition of cake Acid reagent Yield: Solids Protein Lipid solids incake/ solids in bean a. HCl 38 37.1 21.8 9. b. H,SO 38 37.7 22.8 9 c.HCl+0.lM ('aCL, 38 42.1 24.8 11

To the cake there was added 4 percent by weight of solid sodiumchloride, and the mixture was stirred to form a viscous aqueouspreparation containing dissolved protein, dissolved salt and lipid asfollows:

Unhulled soy beans (20 kg) were mixed with aqueous 1 0.1 percent sodiumsulphite solution (200 litres) and milled in a Hobart MCV12 mill, so asto pass a 0.2 mm I gap. The aqueous protein-lipid emulsion formed wasExample 3 This Example, and Example 4, illustrate setting treatments ofa fluid aqueous protein-lipid preparation such 1 as is obtained by theprocedures of Examples 1 and 2.

A preparation obtained following generally the procedure of Example 2and of the composition:

Water 65.4

Solids 34.6

Protein 20.7

Ash 3.6%

Lipid 7.1

was filtered through a 1 mesh (BSS) sieve to remove {The fibres obtainedas described above can be used as a foodstuff, for example aspart-replacement for the meat ordinarily used in the preparation ofbeefburgers or canned reformed meat. The flavour of soybean in materialthus made is only slight, and hardly detectable at all with use of thefibres made in setting bath i).

Example 4 A fluid aqueous protein preparation obtained followinggenerally the procedure of Example 2 was filtered and then extrudedthrough spinnerets of 0.2 mm diameter into water at C. The fibres thusformed (4 kg) were treated with hexane in an extractor of the soxhlettype for 3 hours, using a 15 minute cycle. The residual solvent wasremoved from the fibres by treating them with live steam for 3 hours.The changes in composition that occurred in the conversion of the fluidaqueous protein preparation to the final fibre product are shown below:

Material Water Lipid Protein Ash Fluid preparation 56 16.2 23.1 2.8

Fibres 57.6 16.9 23.4 0.6

Solvent-extracted fibres 52.2 16.8 27.6 0.5

Substitution of groundnuts (peanuts) for the soybeans of the aboveexamples gives essentially similar lipid and water-insolublecarbohydrate, said process comprising finely subdividing the seed in thepresence of water to form an aqueous protein-lipid emulsion containingthe water-insoluble carbohydrate in suspension; separating saidwater-insoluble carbohydrate from the emulsion; acidifying the emulsionto form a coprecipitate of protein and lipid; and separating thecoprecipitate from supernatant liquid; the improvement which consists incarrying out the steps of:

i. mixing the separated coprecipitate of protein and lipid in thepresence of water with an edible watersoluble salt in an amounteffective to form a fluid aqueous protein-lipid-salt preparation inwhich the lipid present in said coprecipitate is distributed and whichcontains protein in a concentration of at 6 least percent by weight; and3. A process according to claim 2, wherein the setting ii. setting thefluid aqueous protein-lipid-salt preparamedium is a lipid-solvent whichcomprises isotion by heat; and propanol. iii. during or subsequent tosetting, contacting the A Process according to Claim 2, wherein theSetting protein-lipid-salt preparation with a lipid solvent, medium is aliquid in which the iiPid is insoluble, and

whereby t f th li id content i dissolved and the extruded set materialformed by extrusion into said the protein/lipid ratio of the preparationis inliquid is subsequently treated with a lipid h icreased, 5. Aprocess according to claim 1, wherein saldedi- 2. A process according toclaim 1, wherein said fluid i water'soiubie Salt Sodluhichiol'ldeaqueous protein-lipid-salt preparation is set by extrul0 AProcess according to Cialm 1, wherein the Seeds sion into a settingmedium maintained at a temperature employed are Soybeansof at least 75C.

2. A process according to claim 1, wherein said fluid aqueousprotein-lipid-salt preparation is set by extrusion into a setting mediummaintained at a temperature of at least 75*C.
 3. A process according toclaim 2, wherein the setting medium is a lipid-solvent which comprisesiso-propanol.
 4. A process according to claim 2, wherein the settingmedium is a liquid in which the lipid is insoluble, and the extruded setmaterial formed by extrusion into said liquid is subsequently treatedwith a lipid solvent.
 5. A process according to claim 1, wherein saidedible water-soluble salt is sodium chloride.
 6. A process according toclaim 1, wherein the seeds employed are soybeans.